Conventional radiator shutters for diesel truck engines comprise a series of pivotal vanes interconnected by parallelogram linkages. When the engine coolant temperature gets above a safe level an air-operated motor actuates the linkages to open the vanes; as the coolant temperature drops below a desired value the air-operated motor reverses the linkage motion to close the vanes. The vanes act like butterfly valves to control the air stream through the radiator.
When the vehicle is operated in arctic temperatures conventional shutters may have a tendency to "ice up" and stick in the open or closed position. The present invention provides a hollow flexible elastomeric vane structure that is internally pressurized to crack external ice accumulations, thereby preventing such ice accumulations from immobilizing the vanes in the open or closed positions.